@charset "utf-8";
/*
date：2018-11-06. ,
author: Hexiyang ,
author-blog: http://hexiyang.cn
*/

.Back {
  position: fixed;
  left: 1rem;
  top: 1rem;
  padding: 1rem;
  z-index: 2;
  background-color: rgba(0,0,0,.4);
  border-radius: 50%;
  line-height: 1;
  color: white;
}